[Driver] Move detectLibcxxIncludePath to ToolChain

This helper method is useful even outside of Gnu toolchains, so move
it to ToolChain so it can be reused in other toolchains such as Fuchsia.

Differential Revision: https://reviews.llvm.org/D88452

1 files changed, 23 insertions, 0 deletions

diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 8991216..8e98e32 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -924,6 +924,29 @@ void ToolChain::addExternCSystemIncludeIfExists(const ArgList &DriverArgs,
   }
 }
 
+std::string ToolChain::detectLibcxxIncludePath(StringRef Base) const {
+  std::error_code EC;
+  int MaxVersion = 0;
+  std::string MaxVersionString;
+  for (llvm::vfs::directory_iterator LI = getVFS().dir_begin(Base, EC), LE;
+       !EC && LI != LE; LI = LI.increment(EC)) {
+    StringRef VersionText = llvm::sys::path::filename(LI->path());
+    int Version;
+    if (VersionText[0] == 'v' &&
+        !VersionText.slice(1, StringRef::npos).getAsInteger(10, Version)) {
+      if (Version > MaxVersion) {
+        MaxVersion = Version;
+        MaxVersionString = std::string(VersionText);
+      }
+    }
+  }
+  if (!MaxVersion)
+    return "";
+  SmallString<128> P(Base);
+  llvm::sys::path::append(P, MaxVersionString);
+  return std::string(P.str());
+}
+
 void ToolChain::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                              ArgStringList &CC1Args) const {
   // Header search paths should be handled by each of the subclasses.